High speed document feeding and printing apparatus, such as those used for endorsing food stamps, personal checks and similar documents with a fixed message, generally utilize a print drum cooperating with a platen and an electric motor for driving the print drum. While it is desirable to operate the apparatus at a constant document feed rate, this is difficult to achieve because of the varying loads placed on the motor during the operating conditions of printing and non-printing. The problem is more severe with high speed document feeding and printing apparatus such as an endorser wherein the document feed rate may be of the order of 600 documents per minute.